This invention relates to coaxial cable connecting devices; and more particularly relates to a novel and improved adapter for connecting mini-coax cables to a connector.
Mini-coax cables are increasingly being used in installations having space limitations and where only a short run of cable is needed. Typically, the mini-coax cables are on the order of 2.5 mm. to 4 mm. in diameter. Typical applications for such cables are for security cameras as well as telecommunications. A difficulty in using the smaller cables however is in manually preparing the cable to connect to a post or terminal in the field. For example, there is the problem of separating the conductive and non-conductive layers when preparing the end of the cable for connection and in such a way as to prevent shorting between layers. A typical example is in connecting to a BNC connector having a preassembled crimping ring, such as, that set forth and described in my U.S. Letters Pat. No. 6,352,448. It is extremely difficult to force 2 sleeve on the BNC connector between the dielectric and braided layers and often leads to shorting between the conductive braid layer and center conductor wire or pin. Furthermore, it is important to be able to maintain proper alignment and centering of the interconnecting conductor wire or pin at the lead end of the cable when advancing into position within the BNC connector as well as to promote ease of positive connection to avoid creating an impedance tending to downgrade the signal through the cable and connector.
From the foregoing, there is a definite need for an adapter for coaxial cables and particularly the smaller diameter cables which will overcome the aforementioned problems and result in a positive, secure connection between the cable and connector in a minimum number of steps.
It is therefore an object of the present invention to provide for a novel and improved adapter for coaxial cables.
It is another, object of the present invention to provide for a novel and improved adapter for small diameter coaxial cables which can be installed in the field in a minimum number of steps with minimal tooling required.
It is a further object of the present invention to provide for a novel and improved adapter for coaxial cable installations which assures accurate alignment between the cable and connector preliminary to crimping of the connector onto the cable and prevents shorting between the cable layers with one another as well as with conductive portions of the connector.
It is a still further object of the present invention to provide for a novel and improved adapter for preparing the end of a coaxial cable for installation into an end connector having a preassembled crimping ring.
In accordance with the present invention, an adapter is provided for connecting the end of a coaxial cable to a hollow connector body wherein the cable is of the type having inner and outer concentric electrical conductors, an annular dielectric separating the conductors and an outer jacket of electrically non-conductive material, the inner and outer conductors being exposed and the inner conductor projecting beyond the dielectric at one end of the cable; and the adapter comprises an extension member including a tip of electrically conductive material provided with a recess into which the inner conductor can be inserted, a first sleeve of electrically non-conductive material surrounding the dielectric layer, and a second sleeve of electrically conductive material surrounding the exposed end of the outer conductor. In a preferred form thereof, the first sleeve is dimensioned such that it can be advanced over the extension tip and will cause a trailing end of the extension tip to be compressed snugly into firm engagement with the central conductor pin. Further, the second sleeve is dimensioned to advance over both the tip and plastic sleeve, and a reduced or thicker portion of the second sleeve will bear against an enlarged portion of the first sleeve and at the same time stiffen or rigidify the entire adapter assembly. The sleeves are dimensioned such that a standard size crimping ring, for example, on a BNC connector will cause the second sleeve to be compressed into sealed engagement with the end of the cable, and the first sleeve will insulate the outer conductive braided layer from to prevent shorting. In addition, a trailing end of the second sleeve is slotted to divide the trailing end into prong-like segments having internal and external teeth so that the trailing end of the second sleeve can be compressed into engagement with the cable without crushing the dielectric layer.
Further in accordance with the present invention, one method of installing a cable of the type described in a hollow connector body comprises the steps of inserting the inner conductor into a recessed end of an extension member, inserting the extension member into a first sleeve composed of electrically non-conductive material until the first sleeve bears against an end of the material, and inserting the extension member and first sleeve into a second sleeve and advancing the second sleeve over the first sleeve until a trailing end of the second sleeve overlies a portion of the outer conductor, and the second sleeve can be contracted into engagement with the outer conductor.
The above and other objects, advantages and features of the present invention will become more readily appreciated and understood from a consideration of the following detailed description of a preferred form of the present invention when taken together with the accompanying drawings in which: